In a gas turbine engine, air is pressurized in a compressor, mixed with fuel in a combustor, and ignited for generating hot combustion gases that flow downstream into a turbine so as to extract energy therefrom. The turbine generally includes a number of turbine nozzles with each of the nozzles having a number of circumferentially spaced apart nozzle vanes supported by integral outer and inner bands.
Overall engine efficiency is related to the temperature of the combustion gases. As a result, ceramic matrix composite (“CMC”) materials have been used to form the nozzle vanes because of their high temperature capabilities. Although the CMC vanes may not require cooling, the attachments to the vane, such as the strut and the metallic bands, do require cooling. In order to minimize the parasitic losses and improve the efficiency of the overall turbine engine, the amount of cooling air used to cool the metallic attachments should be minimized. Specifically, effective sealing will minimize the cooling air leakage and thereby improve the efficiency of the turbine engine. Effective sealing design also will prevent the ingestion of hot gas into the metallic attachment section of the turbine and thereby increase the life of the metallic components.
Thus, there is a need for improved sealing methods between a CMC vane and the associated metallic components. The seals preferably will be easy to install, have an adequate lifetime, provide increased efficiency, and substantially prevent the leakage of the cooling air.